Sounds like an Iron OD. When you say you add 5ml a week do you do this in
one go or a little every day? Maybe adding a touch daily or every second day
might solve your problem. As another poster said it would be a good idea to
add some plants, maybe floaters as they absorb the most nutrients quickly.

HTH
Regards
Cam

"coigula" wrote in message
...
Hi

I have the growth of a long filimentous type green algae that grows in
threads in the top half of the aquarium. I have little or no other types
of algae clearly visible.

I run 2 54w full spectrum daylights over a std 55 gallon for 8-10hrs per
day by a timer. Is the source of this algae too much light? I can
easily raise the height of the suspended light or shorten the duration.
Otherwise plant growth is excellent. I run 80ppm as caco3 alkalinity at
set ph controller to 6.9pH.

I use 5 ml Tropica master grow weekly as well.

Drew